Debian

Debian

Debian 7.0 (Wheezy) with GNOME 3
Company / developer	Debian Project
OS family	Unix-like
Working state	Current
Source model	Open source
Initial release	16 August 1993; 19 years ago (1993-08-16)
Latest stable release	7.1 (Wheezy) (June 15, 2013; 4 days ago (2013-06-15)) [±][1]
Latest unstable release	Debian Testing (Jessie) (6 May 2013; 44 days ago (2013-05-06)) [±][2]
Available language(s)	Multilingual (more than 73)[3]
Update method	APT (several front-ends available)
Package manager	dpkg
Supported platforms	i386, AMD64, PowerPC, SPARC, ARM, MIPS, S390, IA-64
Kernel type	Monolithic: Linux, kFreeBSD (experimental: Micro: Hurd)
Userland	GNU Core Utilities
Default user interface	GNOME
License	Free software, mainly the GNU GPL, and other licenses[4]
Official website	www.debian.org

Debian /ˈdɛbiən/ is an operating system composed of free software mostly carrying the GNU General Public License.^[5] The operating system is developed by an internet collaboration of volunteers aligned with The Debian Project. Its focus of different kernels makes it appeal to different titles, such as Debian GNU/Linux and kFreeBSD.^[6] Debian names its operating systems with kernel names and the word GNU, since Debian depends on its software development using GNU tools.

Debian GNU/Linux is one of the most popular Linux distributions for personal and Internet server machines.^{[7][8][9][10]} Debian is seen as a solid Linux, and as a consequence has been used as a base for other Linux distributions. Debian has been forked many times, but is not affiliated with derivatives.

The vitality the Debian project plays in open source is demonstrated in pursuit of advancing development and security patches in relation to its strong participation of CVE compatibility efforts.^[11]

Information sources related to the many derivatives can be found with internet and wikipedia pages: Debian derivatives.

Contents 1 Features 1.1 Desktop environments 1.2 Debian-Live 1.3 Embedded systems 1.4 Packages 1.4.1 Package management 1.4.1.1 The dpkg database 1.4.1.2 The dpkg command 1.4.1.3 APT tools for online repositories 1.4.1.3.1 The gdebi tool and other front-ends 1.5 Repositories 1.5.1 Official 1.5.2 Non-free and Unofficial repositories 1.5.2.1 Third-party 1.6 Hardware support 1.6.1 Hardware requirements 1.6.2 Architecture ports 1.6.2.1 Stable ports 1.6.2.2 Unstable ports 1.6.2.3 Unofficial ports 2 Policies 2.1 Organization 2.2 Project leaders 2.3 Release managers 2.4 Developer recruitment, motivation, and resignation 2.5 Development procedures 2.6 Package maintenance 2.7 Debian Security Announcement (DSA) 3 History 3.1 Releases 3.1.1 Security updates 3.1.2 Time-based development schedule 3.1.3 Debian release code names 3.2 Timeline 3.3 1993–1998 3.4 1999–2004 3.5 2005–present 4 Reception 5 See also 6 References 7 Further reading 8 External links

Features[edit]

The Debian project released a new kernel as of Wheezy's release date: the Debian GNU/kFreeBSD kernel. Debian now supports two kernels, Linux and kFreeBSD, and offers other kernels as development works(GNU Hurd and NetBSD). This project's new kernel has recently come out of preview but still lacks the amount of software available as on Debian's Linux. The kernel is offered for Intel/AMD 32-bit and 64-bit architecture machines.^[12] Wheezy is officially supported on ten machine architectures and also brought support for two new architectures: s390x and armhf.

Debian is still primarily known as a Linux distribution with access to online repositories hosting over 37,500 software packages.^[13] Debian officially hosts free software on its repositories but also allows non-free software to be installed. Debian includes popular programs such as LibreOffice,^[14] Iceweasel (a rebranding of Firefox), Evolution mail, CD/DVD writing programs, music and video players, image viewers and editors, and PDF viewers. The cost of developing all the packages included in Debian 5.0 lenny (323 million lines of code) using the COCOMO model, has been estimated to be about US$ 8 billion.^[15] Ohloh estimates that the codebase (54 million lines of code) using the same model, would cost about US$ 1 billion to develop.^[16]

Debian offers 10 DVD and 69 CD images for download and installation, but only the first optical iso image of any of its downloadable sets is sufficient. Debian requires the first installable image, but uses online repositories for additional software. Debian's basic installation requires only the first CD or DVD of its release in order to have a working desktop experience. The Wheezy release offers to install a variety of default Desktops from its DVD boot menu(GNOME, KDE, XFCE, and LXDE) and allows visually-impaired people to use its installer. The new feature in Debian's latest installer of Wheezy for the visually-impaired supports a mode which is textual but performs audio output for each stage of installation. Debian offers different network installation methods for expert users. A minimal install of Debian is available via the 'netinstall' CD, whereby Debian is installed with just a base and later additional software can be downloaded from the internet.^[17]

Debian's new form of installation-from-USB has been supported since its sixth edition. Debian supports this capability inside its first iso-file of any of its install media sets (whether CD or DVD) and does not require the help of 'extraction tools' such as unetbootin. This new feature is called Hybrid iso in which an .iso file is dumped to USB. Debian is one of the few Linux distributions offering this feature with its install iso media, and other distributions are starting to adopt alike.

Other notable new features in Debian's latest release includes the following. Multiarch, which allows 32-bit Linux software to run on 64-bit operating system installs.^[18] Improved multimedia support which allows users to no longer rely on using third-party repositories. Compiled packages with hardened security flags. App Armor, which can protect a system against unknown vulnerabilities. And systemd, which shipped as a technology preview.

Debian's install-media is distributed via downloadable CD/DVD images from its mirrored sites,^[19] BitTorrent, jigdo and from optional retailers.^[20]

Desktop environments[edit]

Debian offers stable and testing CD images specifically built for GNOME (the default), KDE Plasma Workspaces, Xfce and LXDE.^[21] Less common window managers such as Enlightenment, Openbox, Fluxbox, GNUstep, IceWM, Window Maker can also be installed.

Debian-Live[edit]

A Debian-Live system is officially supported by the Debian project. A Debian-Live system can be booted from removable media (CDs, DVDs, USB thumb drive), and possibly from netboot images.^[22] Debian-Live allows a user to try a Debian desktop without actually installing it but with the penalty of no persistent storage and it would be running with degraded speed. Debian-Live comes tailored and made available as a variety of community prebuilds, such as GNOME, KDE Plasma Workspaces, Xfce, LXDE, and rescue boot environments. An option for permanently installing Debian on a hard disk is also made available from these boot environments. Personalized Debian-Live images can be built with the live-build tool,^[23] in which images are generated for CD/DVD/USB drives and for netboot purposes. Live-magic is another tool used for personalizing Debian-Live images, along with the assistance of a graphical interface.

The official standard Debian-live images are available only for the i386 and amd64 related architectures as indicated from the website http://www.debian.org/CD/live/

Embedded systems[edit]

Recent releases of Debian support an increasing number of ARM-based NAS devices. The cheap NSLU2 was supported by Debian 4.0 and 5.0^[24] and can be upgraded to Debian 6.0 although there are problems with a 6.0 clean install.^[25] Debian 5.0 added support for the Buffalo Kurobox Pro,^[26] and Debian 6.0 for the SheevaPlug.^[27]

Other NAS devices supported by Debian, but perhaps not so widely used by home users, include GLAN Tank^[28] and Thecus N2100 as of Debian 4.0,^[29] QNAP Turbo Station (TS-109, TS-209, TS-409) and HP mv2120 as of Debian 5.0,^[26] and QNAP Turbo NAS TS-11x, TS-21x and TS-41x, OpenRD, Lanner EM7210 and Intel SS4000-e as of Debian 6.0.^[27]

Packages[edit]

Package management[edit]

Debian's official standard for administering packages on its system is the apt toolset. Though for many years apt-get has been the defacto tool for administering packages on Debian, suggestions point aptitude should be used instead as aptitude supports better search on package metadata.^[30]

The dpkg database[edit]

dpkg is the storage information center of installed packages and provides no configuration for accessing online repositories. The dpkg database is located at /var/lib/dpkg/available and contains the list of "installed" software on the current system.

The dpkg command[edit]

The dpkg command tool is used for the dpkg database without capability of accessing online repositories.^[31] The command can work with local .deb package files as well as information from the dpkg database.

APT tools for online repositories[edit]

An APT tool allows administration of an installed Debian system for retrieving and resolving package dependencies from online repositories. APT tools share dependency information(/etc/apt configuration files) and downloaded cache .deb files(/var/cache/apt/archives). APT tools depend on verifying what is installed in the dpkg database in order to determine missing packages for requested installs.

• aptitude is a command tool and offers a TUI interface. This command's support is self-contained for full features of APT administration
• apt-get and apt-cache are command tools of the standard APT-class toolset apt package. The package is called "apt" and supplies the command "apt-cache" as well as "apt-get". "apt-get" installs and removes packages. "apt-cache" is used for searching packages and displaying package information.

Package installed with aptitude.

The gdebi tool and other front-ends[edit]

• gdebi is an APT which can be used in command-line and on the GUI. gdebi combines the functionality of the dpkg tool and APT package resolving with online repositories. The local .deb file in the GUI environment's file manager can be associated to be opened with gdebi providing a graphical experience of installing packages via double clicking. gdebi can also install a local .deb file via the command line alike the dpkg command, but with access to online repositories. If gdebi is requested to install a local .deb file that requires to install a dependency, it then searches the repositories as defined in the common APT configuration folder (/etc/apt) and performs to resolving and downloading missing packages.

There are various front-ends for APT, both graphical and command-line based. Graphical applications include Software Center, Synaptic and Apper.

Repositories[edit]

The Debian Project offers three distributions, each with different characteristics. The distributions include packages which comply with the Debian Free Software Guidelines (DFSG), which are included inside the main repositories.^[33] Debian also officially supports the optional backports repository for the stable distribution.^[34]

Official[edit]

• stable, currently aliased wheezy, is the current release that has stable and well-tested software. Stable is made by freezing testing for a few months where bugs are fixed to make the distribution as stable as possible; then the resulting system is released as stable. It is updated only if major security or usability fixes are incorporated. After Debian 6.0, new releases will be made every two years.^[35] Stable's CDs and DVDs can be found in the Debian website.^[33]
• backports: This repository provides more recent versions than stable for some software. It is mainly intended for users of stable who need a newer version of a particular package.
• testing, currently aliased jessie, is what the next major release will be and is currently being tested. The packages included in this distribution have had some testing in unstable but they may not be completely fit for release yet. It contains more modern packages than stable but older than unstable. This distribution is updated continually until it enters the "frozen" state. Security updates for testing distribution are provided by Debian testing security team. Testing's CDs and DVDs can be found on the Debian website.^[33]
• unstable, permanently aliased sid, repository contains packages currently under development; it is updated continually. This repository is designed for Debian developers who participate in a project and need the latest libraries available, or for those who like to "live on the edge", so it will not be as stable as the other distributions. There are no official CDs/DVDs because it is rapidly changing and the project does not support it, although CD and DVD images of sid are built quarterly by aptosid. Additionally, the other two distributions can be upgraded to unstable.^[33]

Depreciating repositories in Debian:

• oldstable, presently aliased squeeze, is the prior stable release. It is supported until 1 year after a new stable is released. Debian recommends to update to the new stable once it has been released.^[36]
• snapshot: The snapshot repositories provide older versions of other repositories. They may be used to install a specific older version of some software.

Other repository in Debian:

• experimental: is meant to be a temporary staging area of highly experimental software for developers. Even though it's documented as a 'distribution' branch from Debian's documentation, many dependency packages that fulfill experimental software are commonly resolved with the unstable branch. This branch of experimental software is not as documented as the other branches as it shouldn't even be referenced by advanced users.^[37]

Non-free and Unofficial repositories[edit]

The Debian Free Software Guidelines (DFSG) defines its distinctive meaning of the word "free" as in "free and open source software" (FOSS), although it is not endorsed by the Free Software Foundation or GNU foundation; reason being Debian's servers includes and supports a proprietary repository and documentation that recommends non-free software.^{[38][39][40][41]} In accordance with its guidelines, a relatively small number of packages are excluded from the distributions' main repositories and included inside the non-free and contrib repositories. These two repositories are not officially part of Debian GNU/Linux. The Debian project offers its distribution without non-free repositories but can be adopted manually after initial setup.

• non-free: repositories include packages which do not comply with the DFSG (this does not usually include legally questionable packages, like libdvdcss).^[33]
• contrib: repositories include packages which do comply with the DFSG, but may fail other requirements. For instance, they may depend on packages which are in non-free or requires such for building them.^[33]

Third-party[edit]

These repositories are not part of the Debian Project, they are maintained by third party organizations. They contain packages that are either more modern than the ones found in stable or include packages that are not included in the Debian Project for a variety of reasons such as: e.g. possible patent infringement, binary-only/no sources, or special licenses that are too restrictive. Their use requires precise configuration of the priority of the repositories to be merged; otherwise these packages may not integrate correctly into the system, and may cause problems upgrading or conflicts between packages from different sources. The Debian Project discourages the use of these repositories as they are not part of the project.

Hardware support[edit]

Hardware requirements[edit]

Debian has no hardware requirements beyond those of the Linux kernel and the GNU tool-sets (gcc, coreutils, bash, etc.). Therefore, any architecture or platform to which these packages have been ported, and for which a Debian port exists, can run Debian.^[42]

Linux, and therefore Debian, supports the use of multiple processors in a system (symmetric multiprocessing). This does not inhibit support for single-processor systems.^[42]

Debian's recommended system requirements differ depending on the level of installation, which corresponds to increased numbers of installed components:^[43]

Install desktop	RAM minimum[43]	RAM recommended[43]	Hard drive space used[43]
No	64 MB	256 MB	1 GB
Yes	128 MB	512 MB	5 GB

A 1 GHz processor is the minimum recommended for desktop systems.^[43]

The real minimum memory requirements are much less than the numbers listed in this table. Depending on the architecture, it is possible to install Debian with as little as 20 MB RAM for s390 or 48 MB RAM for i386 and AMD64. Similarly, disk space requirements, which depend on the packages to be installed, can also be reduced.^[43] Emdebian (embedded Debian) improves installation to devices with minimal disk space, partially by removing documentation and installing only needed translations. In its Grip and Baked form it is binary compatible.

It is possible to run graphical user interfaces on older or low-end systems, but the installation of window managers instead of desktop environments is recommended, as desktop environments are more resource-intensive.^[43] For example, the LXDE desktop environment was released with lenny and has much lower processor and memory usage compared with GNOME or KDE Plasma Desktop.^[44]

Depending on the nature of the server, RAM and disk space requirements can vary widely.^[43]

Architecture ports[edit]

Most software packages in the official Debian repositories are compiled for an abundance of available and older instruction sets.

Stable ports[edit]

As of the current stable release, the official ports are:^[45]

• i386: x86 architecture designed for Intel/AMD 32-bit PCs. Also compatible with but not recommended on Intel/AMD 64-bit PCs^[46]
• amd64: x86-64 architecture designed for AMD/Intel 64-bit PCs
• armel: little-endian ARM architecture (Instruction set ARMv4) on RiscPC and various embedded systems (EABI)
• ia64: Intel Itanium (IA-64) architecture
• kfreebsd-i386: Kernel of FreeBSD on x86 architecture
• kfreebsd-amd64: Kernel of FreeBSD on x86-64 architecture
• mips, mipsel: MIPS architecture (big-endian and little-endian)
• powerpc: PowerPC architecture
• s390: IBM ESA/390 architecture and z/Architecture
• sparc: Sun SPARC architecture on sun4u/v systems

Unstable ports[edit]

In the current official unstable distribution there are following ports:

• hurd-i386: GNU Hurd kernel on x86 architecture
• armhf:^[47] ARM (Instruction set ARMv7) hard-float architecture requiring hardware with a floating-point unit (FPU)
• s390x: IBM ESA/390 architecture and z/Architecture with 64-bit userland

Unofficial ports[edit]

Unofficial ports are also available as part of the unstable distribution at http://www.debian-ports.org:

• alpha: DEC Alpha architecture
• hppa: HP PA-RISC architecture
• m68k: Motorola 68k architecture on Amiga, Atari, Macintosh and various embedded VME systems
• powerpcspe: PowerPCSPE architecture (binary-incompatible variant of the PowerPC)
• ppc64: PowerPC64 architecture supporting 64-bit PowerPC CPUs with VMX
• sh4: Hitachi SuperH architecture
• sparc64: Sun SPARC architecture with 64-bit userland
• x32: 32-bit userland for modern amd64 processors, incompatible with i386

The m68k port was the second official one in Debian, and has been part of five stable Debian releases. Due to its failure to meet the release criteria, it was dropped before the release of etch but is in current status of being revived. The arm (OABI,^[48] <armv4t), alpha and hppa ports were dropped before the release of squeeze.

Policies[edit]

Debian is known for its serious manifesto social contract and policies.^[49] Debian's policies and team efforts focus on collaborative software development and testing processes and dedicates lengthy development time between unstable and stable release cycles. As a result of its strictly guarded policies, a new distribution release for Debian tends to occur every one to two years.^[50] The strategy policies used by the Debian project for minimizing software bugs, albeit with longer release cycles, has allowed it to remain one of the most stable and secure Linux distributions.

Organization[edit]

The Debian Project is a volunteer organization with three foundational documents:

• The Debian Social Contract defines a set of basic principles by which the project and its developers conduct affairs.^[49]
• The Debian Free Software Guidelines define the criteria for "free software" and thus what software is permissible in the distribution, as referenced in the Social Contract. These guidelines have also been adopted as the basis of the Open Source Definition. Although it can be considered a separate document for all practical purposes, it formally is part of the Social Contract.^[49]
• The Debian Constitution describes the organizational structure for formal decision-making within the Project, and enumerates the powers and responsibilities of the Debian Project Leader, the Debian Project Secretary, and the Debian Developers generally.^[51]

Debian is developed by over three thousand volunteers.^[52] Each of them sustains some niche in the project, be it package maintenance, software documentation, maintaining the project infrastructure, quality assurance, or release coordination. Package maintainers have jurisdiction over their own packages, although packages are increasingly co-maintained. Other tasks are usually handled by the domain of smaller, more collaborative groups of developers.

Debian is supported by donations through several nonprofit organizations around the world. Most important of these is Software in the Public Interest,^[53] the owner of the Debian trademark and umbrella organization for various other community free software projects.^[54]

The project maintains official mailing lists and conferences for communication and coordination between developers.^[55] For issues with single packages or domains, a public bug tracking system is used by developers and end-users. Informally, Internet Relay Chat channels (primarily on the OFTC and freenode networks) are used for communication among developers and users also.

Together, the Developers may make binding general decisions by way of a General Resolution or election. All voting is conducted by Cloneproof Schwartz Sequential Dropping, a Condorcet method of voting. A Project Leader is elected once per year by a vote of the Developers; in April 2010, Stefano Zacchiroli was voted into this position, succeeding Steve McIntyre. The Debian Project Leader has several special powers, but this power is far from absolute and is rarely used. Under a General Resolution, the Developers may, among other things, recall the leader, reverse a decision by him or his delegates, and amend the constitution and other foundational documents.

The Leader sometimes delegates authority to other developers in order for them to perform specialized tasks. Generally this means that a leader delegates someone to start a new group for a new task, and gradually a team gets formed that carries on doing the work and regularly expands or reduces their ranks as they think is best and as the circumstances allow.

A role in Debian with a similar importance to the Project Leader's is that of a Release Manager. Release Managers set goals for the next release, supervise the processes, and make the final decision as to when to release.^[56][57]

Project leaders[edit]

The Debian Project Leader (DPL) is the public face of the project and defines the current direction of the project.^[58] The project has had the following leaders:^[59]

• Ian Murdock (August 1993 – March 1996), founder of the Debian Project
• Bruce Perens (April 1996 – December 1997)
• Ian Jackson (January 1998 – December 1998)
• Wichert Akkerman (January 1999 – March 2001)
• Ben Collins (April 2001 – April 2002)
• Bdale Garbee (April 2002 – April 2003)
• Martin Michlmayr (March 2003 – March 2005)
• Branden Robinson (April 2005 – April 2006)
• Anthony Towns (April 2006 – April 2007)
• Sam Hocevar (April 2007 – April 2008)
• Steve McIntyre (April 2008 – April 2010)
• Stefano Zacchiroli (April 2010 – April 2013)
• Lucas Nussbaum (April 2013 – present)^[60]

A supplemental position, Debian Second in Charge (2IC), was created by Anthony Towns. Steve McIntyre held the position between April 2006 and April 2007. From April 2009 to April 2010 this position was held by Luk Claes. Stefano Zacchiroli abandoned this unofficial position when elected in April 2010.^[61]

Release managers[edit]

• Brian C. White (1997–1999)
• Richard Braakman (1999–2000)
• Anthony Towns (2000–2004)
• Steve Langasek, Andreas Barth and Colin Watson (2004–2007)
• Andreas Barth and Luk Claes (2007–2008)
• Luk Claes and Marc Brockschmidt (2008–2009)
• Luk Claes and Adeodato Simó (2009–2010)
• Adam D. Barratt and Neil McGovern (2010–present)^[62]

Note that this list includes the active release managers; it does not include the release assistants (first introduced in 2003) and the retiring managers ("release wizards").^[56]

Developer recruitment, motivation, and resignation[edit]

The Debian project has a steady influx of applicants wishing to become developers. These applicants must undergo an elaborate vetting process which establishes their identity, motivation, understanding of the project's goals (embodied in the Social Contract), and technical competence.^[63]

Debian Developers join the Project for a number of reasons; some that have been cited in the past include:^[64]

• A desire to contribute back to the free-software community (practically all applicants are users of free software)
• A desire to see some specific software task accomplished (some view the Debian user community as a valuable testing or proving ground for new software)
• A desire to make, or keep, free software competitive with proprietary alternatives
• A desire to work closely with people who share some of their aptitudes, interests, and goals (there is a very strong sense of community within the Debian project which some applicants do not experience in their paid jobs)
• A simple enjoyment of the iterative process of software development and maintenance

Debian Developers may resign their positions at any time by orphaning the packages they were responsible for and sending a notice to the developers and the keyring maintainer (so that their upload authorization can be revoked).

Development procedures[edit]

Software packages in development are either uploaded to the project distribution named unstable (also known as sid), or to the experimental repository. Software packages uploaded to unstable are normally versions stable enough to be released by the original upstream developer, but with the added Debian-specific packaging and other modifications introduced by Debian developers. These additions may be new and untested. Software not ready yet for the unstable distribution is typically placed in the experimental repository.^[65]

After a version of a software package has remained in unstable for a certain length of time (depending on the urgency of the software's changes), that package is automatically migrated to the testing distribution. The package's migration to testing occurs only if no serious (release-critical) bugs in the package are reported and if other software needed for package functionality qualifies for inclusion in testing.^[65]

Since updates to Debian software packages between official releases do not contain new features, some choose to use the testing and unstable distributions for their newer packages. However, these distributions are less tested than stable, and unstable does not receive timely security updates. In particular, incautious upgrades to working unstable packages can sometimes seriously break software functionality.^[66] Since September 9, 2005^[67] the testing distribution's security updates have been provided by the testing security team.^[68]

After the packages in testing have matured and the goals for the next release are met, the testing distribution becomes the next stable release. The timing of the release is decided by the Release Managers, and in the past the exact date was rarely announced earlier than a couple of weeks beforehand.^[69]

Package maintenance[edit]

Each Debian software package has a maintainer who keeps track of releases by the "upstream" authors of the software and ensures that the package is compliant with Debian Policy, coheres with the rest of the distribution, and meets the standards of quality of Debian. In relations with users and other developers, the maintainer uses the bug tracking system to follow up on bug reports and fix bugs. Typically, there is only one maintainer for a single package, but, increasingly, small teams of developers "co-maintain" larger and more complex packages and groups of packages.^[70]

Periodically, a package maintainer makes a release of a package by uploading it to the "incoming" directory of the Debian package archive (or an "upload queue" which periodically batch-transmits packages to the incoming directory). Package uploads are automatically processed to ensure that they are well-formed (all the requisite files are in place) and that the package is digitally signed by a Debian developer using OpenPGP-compatible software. All Debian developers have individual cryptographic key pairs.^[71] Packages are signed to be able to reject uploads from hostile outsiders to the project, and to permit accountability in the event that a package contains a serious bug, a violation of policy, or malicious code.

If the package in incoming is found to be validly signed and well-formed, it is installed into the archive into an area called the "pool" and distributed every day to hundreds of mirrors worldwide. Initially, all package uploads accepted into the archive are only available in the "unstable" suite of packages, which contains the most up-to-date version of each package.

However, new code is also untried code, and those packages are only distributed with clear disclaimers. For packages to become candidates for the next "stable" release of the Debian distribution, they first need to be included in the "testing" suite. For a package to be included in testing:^[72][73]

• It must have been in unstable for the appropriate length of time (the exact duration depends on the "urgency" of the upload)
• It must not have a greater number of "release-critical" bugs filed against it than the current version in testing. Release-critical bugs are those bugs which are considered serious enough that they make the package unsuitable for release.
• It must be compiled for all release architectures the package claims to support (e.g.: the i386-specific package gmod can be included in "testing")
• All of its dependencies must either be satisfiable by packages already in testing, or be satisfiable by the group of packages which are going to be installed at the same time.
• The operation of installing the package into testing must not break any packages currently in testing.

Thus, a release-critical bug in a package on which many packages depend, such as a shared library, may prevent many packages from entering the testing area, because that library is considered deficient.

Periodically, the Release Manager publishes guidelines to the developers in order to ready the release, and in accordance with them eventually decides to make a release. This occurs when all important software is reasonably up-to-date in the release-candidate suite for all architectures for which a release is planned, and when any other goals set by the Release Manager have been met. At that time, all packages in the release-candidate suite ("testing") become part of the released suite ("stable").

It is possible for a package, particularly an old, stable, and seldom-updated one, to belong to more than one suite at the same time. The suites are simply collections of pointers into the package "pool" mentioned above.

Debian Security Announcement (DSA)[edit]

The Debian Project, being free software, handles security policy through public disclosure rather than through security through obscurity. Many advisories are coordinated with other free software vendors (Debian is a member of vendor-sec) and are published the same day a vulnerability is made public. Debian has a security audit team that reviews the archive looking for new or unfixed security bugs. Debian also participates in security standardization efforts: the Debian security advisories are compatible with the Common Vulnerabilities and Exposures (CVE) dictionary, and Debian is represented in the Board of the Open Vulnerability and Assessment Language (OVAL) project.^[74]

The Debian Project offers extensive documentation and tools to harden a Debian installation both manually and automatically.^[75] SELinux (Security-Enhanced Linux) packages are installed by default though not enabled.^[44] Debian provides an optional hardening wrapper but does not compile their packages by default using gcc features such as PIE and buffer overflow protection to harden their software, unlike Ubuntu, Fedora and Hardened Gentoo among others.^[76] These extra features greatly increase security at a performance cost of 1% in 32-bit and 0.01% in 64-bit.^[77]

It is a release goal for Debian 7.0 (wheezy) "to update as many packages as possible to use security hardening build flags via dpkg-buildflags. These flags enable various protections against security issues such as stack smashing, predictable locations of values in memory, etc."^[78]

History[edit]

Releases[edit]

As of May 2013^[update], the latest stable release is version 7.0, code name wheezy. When a new version is released, the prior stable version becomes oldstable. As of May 2013^[update], this is version 6.0, code name squeeze.

In addition, a stable release gets minor updates (called point releases). The numbering scheme for the point releases up to Debian 4.0 was to include the letter r (for release) after the main version number (e.g. 4.0) and then the number of the point release; for example, the latest point release of version 4.0 (etch) as of 8 December 2010 is 4.0r9.^[79] From Debian 5.0 (lenny), the numbering scheme of point releases has been changed and conforms to the GNU version numbering standard; so, for example, the first point release of Debian 5.0 was 5.0.1 (instead of 5.0r1).^[80]

Security updates[edit]

The Debian security team releases security updates for the latest stable major release, and for the prior stable release for one year.^[66] Version 4.0 etch was released on 8 April 2007, and the security team supported version 3.1 Sarge until 21 March 2008. For most uses it is strongly recommended to run a system which receives security updates. The testing distribution also receives security updates, but not in as timely a manner as stable.^[81]

Time-based development schedule[edit]

For Debian 6.0 (squeeze) a new policy of time-based development freezes on a two-year cycle was announced. Time-based freezes are intended to allow the Debian Project to blend the predictability of time based releases with its policy of feature based releases. The new freeze policy aims to provide better predictability of releases for users of the Debian distribution, and to allow Debian developers to do better long-term planning. Debian developers expect that a two-year release cycle will give more time for disruptive changes, reducing inconveniences caused for users. Having predictable freezes was expected to reduce overall freeze time. The squeeze cycle was intended to be especially short to "get into the new cycle".^[35] However this short freeze cycle for squeeze was abandoned.^[82]

Debian release code names[edit]

The code names of Debian releases are names of characters from the film Toy Story. The unstable, development distribution is permanently nicknamed sid, after the emotionally unstable next-door neighbor boy who regularly destroyed toys.^[65] The current release wheezy is named after the rubber toy penguin in Toy Story 2.^[83] The release after wheezy will be named jessie, after the cowgirl in Toy Story 2 and Toy Story 3.^[84]

Timeline[edit]

Debian has made twelve major stable releases:^[53]

Legend:	Old version	Older version, still supported	Current version	Latest preview version	Future release

TBA stands for to be announced.

Version	Code name	Release date	Ports	Packages	Supported until	Notes
Old version, no longer supported: 1.1	buzz	1996-06-17	1	474	Old version, no longer supported: 1996-09[85]	dpkg, ELF transition, Linux 2.0[53]
Old version, no longer supported: 1.2	rex	1996-12-12	1	848	Old version, no longer supported: 1996[citation needed]	-
Old version, no longer supported: 1.3	bo	1997-06-05	1	974	Old version, no longer supported: 1997[citation needed]	-
Old version, no longer supported: 2.0	hamm	1998-07-24	2	≈ 1,500	Old version, no longer supported: 1998	glibc transition, new architecture: m68k[53]
Old version, no longer supported: 2.1	slink	1999-03-09	4	≈ 2,250	Old version, no longer supported: 2000-12	APT, new architectures: alpha, sparc[53]
Old version, no longer supported: 2.2	potato	2000-08-15	6	≈ 3,900	Old version, no longer supported: 2003-04	New architectures: arm, powerpc[86]
Old version, no longer supported: 3.0	woody	2002-07-19	11	≈ 8,500	Old version, no longer supported: 2006-08	New architectures: hppa, ia64, mips, mipsel, s390[53]
Old version, no longer supported: 3.1	sarge	2005-06-06	11	≈ 15,400	Old version, no longer supported: 2008-04[66]	Modular installer, semi-official amd64 support.
Old version, no longer supported: 4.0	etch	2007-04-08	11	≈ 18,000	Old version, no longer supported: 2010-02-15[87]	New architecture: amd64, dropped architecture: m68k.[88] Graphical installer, udev transition, modular X.Org transition. Final update 4.0r9 was released 2010-05-22.[89]
Old version, no longer supported: 5.0[90]	lenny[91]	2009-02-14[69]	12	≈ 23,000[92]	Old version, no longer supported: 2012-02-06[93]	New architecture/binary ABI: armel.[94] SPARC 32-bit hardware support dropped.[95] Full Eee PC support.[96] Final update 5.0.10 was released 2012-03-10.[97]
Older version, yet still supported: 6.0[98]	squeeze[99]	2011-02-06[100]	9+2[A]	≈ 29,000[100]	Older version, yet still supported: TBA (expected 2014-05)	New architectures/kernels: kfreebsd-i386, kfreebsd-amd64, dropped architectures: alpha, hppa, OABI[48] arm.[100] eglibc instead of glibc.[101] Dependency-based boot sequence, which allows for parallel init script processing.[102] Remove old libraries such as GTK 1.[103] Default Linux kernel purged of non-free firmware.[52]
Current stable version: 7.0[98]	wheezy[83]	2013-05-04[104]	11+2[B]	≈ 37,000[104]	Current stable version: TBA	New architectures: armhf­,[105] s390x.[106] Remove old libraries such as Qt3.[107] Introduce multiarch support.[108]
Future release: 8.0[84]	jessie[84]	TBA	TBA	TBA	Future release: TBA	TBA

^A 9 architectures with Linux kernel + 2 architectures with kernel of FreeBSD^[100]

^B 11 architectures with Linux kernel + 2 architectures with kernel of FreeBSD

Due to an incident involving a CD vendor who made an unofficial and broken release labeled 1.0, an official 1.0 release was never made.^[53]

1993–1998[edit]

Debian was first announced on 16 August 1993 by Ian Murdock,^[109] who initially called the system "the Debian Linux Release".^[110] The word "Debian" was formed as a combination of the first name of his then-girlfriend Debra Lynn and his own first name.^[111] Prior to Debian's release, the Softlanding Linux System (SLS) had been the first Linux distribution compiled from various software packages, and was a popular basis for other distributions in 1993-1994.^[112] The perceived poor maintenance and prevalence of bugs in SLS^[113] motivated Murdock to launch a new distribution.

In 1993 Murdock also released the Debian Manifesto,^[114] outlining his view for the new operating system. In it he called for the creation of a distribution to be maintained in an open manner, in the spirit of Linux and GNU.

The Debian Project grew slowly at first and released the first 0.9x versions in 1994 and 1995. During this time it was sponsored by the Free Software Foundation's GNU Project.^[115] The first ports to other, non-i386 architectures began in 1995, and the first 1.x version of Debian was released in 1996.

In 1996, Bruce Perens replaced Ian Murdock as the project leader. Perens decided to create a social contract for Debian to guarantee the future freedom of the system's contents. He created a first draft, and edited suggestions from a month-long discussion on the Debian mailing lists into the Debian Social Contract and the Debian Free Software Guidelines, defining fundamental commitments for the development of the distribution. He also initiated the creation of the legal umbrella organization, Software in the Public Interest.^[53] Perens developed the project from 40 to 200 developers. He broke apart the "base system", the core packages of Debian, which had been maintained by Murdock alone, and distributed them to many maintainers. He led the conversion of the project from a.out to ELF. He created the BusyBox program to make it possible to run a Debian installer on a single floppy, and wrote a new installer. Perens was also responsible for many policy and design elements of Debian that persist to this day. Perens left the project in 1998.

1999–2004[edit]

The Project elected new leaders and made two more 2.x releases, each including more ports and packages. The Advanced Packaging Tool was deployed during this time and the first port to a non-Linux kernel, Debian GNU/Hurd, was started. The first Linux distributions based on Debian, namely Libranet, Corel Linux and Stormix's Storm Linux, were started in 1999.^[53] The 2.2 release in 2000 was dedicated to Joel Klecker, a developer who died of Duchenne muscular dystrophy.^[116]

In late 2000, the project made major changes to archive and release management, reorganizing software archive processes with new "package pools" and creating a testing distribution as an ongoing, relatively stable staging area for the next release. In the same year, developers began holding an annual conference called DebConf with talks and workshops for developers and technical users.^[53]

In July 2002, the Project released version 3.0, codenamed woody, a stable release which would see relatively few updates until the following release.^[53]

2005–present[edit]

The 3.1 sarge release was made in June 2005. There were many major changes in this release, mostly due to the long time it took to freeze and release the distribution. Not only did this release update over 73% of the software shipped in the prior version, but it also included much more software than prior releases, almost doubling in size with over 9,000 new packages.^[117] A new installer replaced the aging boot-floppies installer with a modular design. This allowed advanced installations (with RAID, XFS and LVM support) including hardware detection, making installations easier for novice users. The installation system also boasted full internationalization support as the software was translated into almost forty languages. An installation manual and comprehensive release notes were released in ten and fifteen different languages respectively. This release included the efforts of the Debian-Edu/Skolelinux, Debian-Med and Debian-Accessibility sub-projects which raised the number of packages that were educational, had a medical affiliation, and ones made for people with disabilities.^[53]

In 2006, as a result of a much-publicized dispute, Mozilla software was rebranded in Debian, with Firefox becoming Iceweasel, Thunderbird becoming Icedove, along with other Mozilla programs. The Mozilla Corporation stated that Debian may not use the Firefox trademark if it distributes Firefox with modifications which have not been approved by the Mozilla Corporation. Two prominent reasons that Debian modifies the Firefox software are to change the artwork and to provide security patches. Debian Free Software Guidelines consider Mozilla's artwork non-free. Debian provides long term support for older versions of Firefox in the stable release, where Mozilla preferred that old versions not be supported but has since included Legacy versions of programs. These software programs developed largely by the Mozilla Corporation were rebranded despite having only minor differences in the source code.^[118]

Debian 4.0 (etch) was released April 8, 2007 for the same number of architectures as in sarge. It included the AMD64 port but dropped support for m68k. The m68k port was, however, still available in the unstable distribution. There were approximately 18,200 binary packages maintained by more than 1,030 Debian developers.^[53]

Debian 5.0 (lenny) was released February 14, 2009 after 22 months of development. It includes more than 25,000 software packages. Support was added for Marvell's Orion platform and for netbooks such as the Asus Eee PC, but support was dropped for 32-bit SPARC machines.^[92] The release was dedicated to Thiemo Seufer, an active developer and member of the community who died in a car accident on December 26, 2008.^[119]

On September 5, 2010, Debian officially acquired the backports service, which provides more recent versions of some software for the stable release of Debian.^[120]

Debian 6.0 (squeeze) was released February 6, 2011 after 24 months of development. For the first time, Debian GNU/kFreeBSD was introduced with this version as a technology preview.^[100]

Debian 7.0 (wheezy) was released May 4, 2013 after 26 months of development. This release attempted to allow more architectures to be supported.^[121]

Reception[edit]

Debian was ranked second only to Ubuntu (which is derived from Debian) for Most Used Linux Distribution for both personal and organizational use in a 2007 survey by SurveyMonkey.com.^[122] Debian won the 2007 poll on Server Distribution of the Year by LinuxQuestions.org.^[123]

Both the Debian distribution and their website have won various awards from different organizations. Debian was awarded the 2004 Readers' Choice Award for Favorite Linux Distribution by the Linux Journal.^[124] A total of fifteen other awards have been awarded throughout Debian's lifetime including Best Linux Distribution.^[125]

Debian has also received negative assessments. In May 2008, a Debian Developer revealed his discovery that changes made in 2006 to the random number generator in the version of the OpenSSL package distributed with Debian and other Debian-based distributions such as Ubuntu or Knoppix, made a variety of security keys vulnerable to a random number generator attack.^[126][127] The security weakness was caused by changes made to the OpenSSL code by another Debian Developer in response to memory debugger warnings.^[128] The security hole was soon patched by Debian and others, but the complete resolution procedure was cumbersome for users because it involved regenerating all affected keys, and it drew criticism to Debian's practice of making Debian-specific changes to software.

Richard Stallman and the Free Software Foundation (FSF) have criticized the Debian Project for providing the non-free repository, rather than excluding this type of software entirely,^[129] an opinion also echoed by some in Debian including the then-Project Leader Wichert Akkerman.^[130] The internal dissent in the Debian Project regarding the non-free section has persisted, but the last time it came to a vote in 2006, a large majority decided to keep it.^[131]

During the release cycles of Woody and Sarge, the Debian Project drew considerable criticism from the free software community because of the long time between stable releases. This triggered the creation of Ubuntu in 2004^{[citation needed]}. Ubuntu has releases every 6 months which are forks of Debian's unstable distribution with bug fixes and other modifications. However, it may be more appropriate to compare Debian releases (which continue to be supported after the release of subsequent versions) to Ubuntu's Long Term Support releases (which are supported for five years for servers and also for five years for desktops starting with Ubuntu 12.04 LTS);^[132] Ubuntu produces a new LTS release every two years, which is therefore similar to Debian's new two-year release cycle for post-Debian 6.0 releases.^[35]

When in need of updated versions of software, it is possible to use Debian testing instead of stable as it usually contains more modern, though slightly less stable packages. Another alternative is to use Debian backports, which are "recompiled packages from testing (mostly) and unstable (in a few cases only, e.g. security updates), so they will run without new libraries (wherever it is possible) on a stable Debian distribution".^[133]

See also[edit]

• Comparison of Linux distributions
• DCC Alliance
• List of Linux distributions

References[edit]

Further reading[edit]

• Hertzog, Raphaël (2012). The Debian Administrator's Handbook. Lulu Press. p. 495. ISBN 9791091414005. 
• Krafft, Martin F. (2005). The Debian System. U.S.A.: No Starch Press. p. 608. ISBN 1-59327-069-0. 
• Mako Hill, Benjamin (2005). Debian GNU/Linux 3.1 Bible. John Wiley & Sons. p. 672. ISBN 0-7645-7644-5. 
• Jurzik, Heike (2005). Debian GNU / Linux. Galileo Press GmbH. p. 630. ISBN 3-89842-627-0. 
• Schoblick, Robert (2005). Debian / GNU Linux. BHV Verlag. p. 767. ISBN 3-8266-8151-7. 
• Bellomo, Michael (2000). Debian GNU/Linux for Dummies. Hungry Minds. p. 324. ISBN 0-7645-0713-3. 
• McCarty, Bill (1999). Learning Debian GNU/Linux. O'Reilly. p. 360. ISBN 1-56592-705-2. 
• Goerzen, John (1999). Debian Gnu/Linux: Guide to Installation and Usage. New Riders Pub. p. 158. ISBN 0-7357-0914-9. 
• Scheetz, Dale (1998). The Debian Linux User's Guide. Linux Press. p. 268. ISBN 0-9659575-1-9. 

External links[edit]

Find more about Debian at Wikipedia's sister projects
	Media from Commons
	Learning resources from Wikiversity
	Textbooks from Wikibooks

• Official Debian website
• Official Debian Live website
• Official Debian wiki
• Debian GNU/Linux at DistroWatch

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